Topical Methyl Aminolevulinate Photodynamic Therapy for the Treatment of Actinic Keratosis

Abstract

Actinic (or solar) keratosis (AK) is a common lesion in fair-skinned ­populations that develops as a result of solar damage to the skin. It is variously referred to as a precancerous lesion that may progress to squamous cell carcinoma (SCC) or as SCC (in situ type). Methyl aminolevulinate photodynamic therapy is still an evolving therapy for actinic keratosis that has good efficacy and provides excellent cosmetic outcomes. The objective of this chapter is to investigate the efficacy of topical methyl aminolevulinate photodynamic therapy (MAL-PDT), its cosmetic outcomes, and its side effects. Multiple electronic databases were searched for studies involving methyl aminolevulinate photodynamic therapy and actinic keratosis. Cochrane Central Register of Controlled Trials was also searched. Cited references of all trials were identified and key review articles were assessed for discussion of relevant outcomes investigated. A total of 11 studies that studied MAL-PDT to treat AK are included in this review. Four studies compared ­MAL-PDT and cryotherapy; three other studies compared MAL-PDT with placebo cream. Only one study compared MAL-PDT with both cryotherapy and placebo, while one report examined MAL-PDT in comparison with aminolevulic acid photodynamic therapy (ALA-PDT). The other two studies compared differences in treatment regimens, dose and treatment interval. MAL-PDT is effective as a treatment for AK lesions especially on the face and scalp. The cosmetic outcome is excellent and superior to cryotherapy in terms of minimum skin discoloration and scarring. The side effects, including skin “burning,” pain, and erythema, have been reported as tolerable.